RESUMO
The aims of this study were to analyze the plasticizing effect of Apis mellifera honey on the mechanical, physicochemical and optical properties of whey protein isolate (WPI) films and to compare the results collected with the plasticizing effect of glycerol on WPI-films. Response surface was applied to optimize the amounts of WPI and glycerol in order to obtain films with higher tensile strength (TS), moderate elongation, and lower water vapor permeability so that they could be used as reference films. Honey was added at different concentrations (60%, 80%, and 100%) of g honey/100 g WPI, as a plasticizer to the WPI-films. In comparison to glycerol-plasticized films, an increase in the percentage of honey produced a reduction of 20 ± 10 to 48 ± 0.5% of TS, a 66 ± 0.5% lower in Young's modulus (WPI-films with 100% honey), and an increase of 186 ± 11% in elongation at break in the WPI-films with 100% honey. Honey-plasticized WPI-films were from 29 ± 11 to 43 ± 3% less permeable to water vapor than glycerol-plasticized WPI films. The mechanical characteristics of the 80% honey formulation did not differ significantly from those of the reference film (p > 0.05). Findings from this study indicate that honey has great potential as a plasticizer in WPI-films.
Assuntos
Abelhas , Mel , Plastificantes , Proteínas do Soro do Leite , Animais , Glicerol/química , Permeabilidade , Plastificantes/química , Vapor , Resistência à Tração , Proteínas do Soro do Leite/químicaRESUMO
The aim of this study was to analyze the mechanisms, stoichiometry, and stability of 4-chlorophenol (4CP) biodegradation kinetics by phenol-acclimated activated sludge using open respirometry. While the removal of 4CP was higher than 98%, the removal of chemical oxygen demand (COD) ranged between 69 and 79% due to the accumulation of an intermediate metabolite. The value obtained from respirometric profiles for the stoichiometric ratio of O2 to 4CP (YO2/4CP) was 1.95 ± 0.04 mol of oxygen consumed per mol of 4CP removed. This YO2/4CP value reflected the action of the oxygenases responsible for the first steps of the aerobic oxidation of 4CP. The 4CP degradation activity decreased noticeably when successive pulses of 4CP were added to the respirometer. A mathematical model was developed to represent the aerobic biodegradation of 4CP. The fitted model adequately predicted the oxygen consumption rate, total phenols, and soluble COD concentrations as a function of time. The results presented could help to predict the dynamic of biodegradation of chlorophenols in a biological wastewater treatment system.
Assuntos
Clorofenóis/química , Fenóis/química , Esgotos/química , Biodegradação Ambiental , Reatores Biológicos , Clorofenóis/metabolismo , Cinética , Modelos Biológicos , Oxigênio/química , Fenóis/metabolismoRESUMO
The aerobic degradation of phenol (PH), catechol (CA), resorcinol (RE), pyrogallol (PY), and hydroquinone (HY) by phenol-acclimated activated sludge was investigated. A Haldane-type dependence of the respiration rate on PH, RE, and HY was observed; CA and PY exhibited a biphasic respiration pattern. According to the initial biodegradation rate, tested compounds were ordered as follows: CA>PH>>PYRE>HY. Also, they exhibited the following degree of toxicity to their own degradation: PY>>CARE>>PH>HY. Oxidation coefficients for PH, PY, RE, and HY were constant as a function of the consecutive additions of the compound. Conversely, an increase of YO/S from 1 to 1.5 molO2 molCA(-1) was observed during repeated additions of CA. The role of some enzymes involved in the aerobic degradation pathways of the tested compounds is discussed and related to the obtained results.
Assuntos
Fenóis/metabolismo , Esgotos/química , Aclimatação , Aerobiose , Bactérias/metabolismo , Biodegradação Ambiental , Cinética , Oxirredução , Consumo de Oxigênio , Fatores de TempoRESUMO
In this paper respirometric techniques were used to study the effect of pH, phenol and dissolved oxygen (DO) concentrations on the phenol biodegradation kinetics by activated sludges. In addition, a mathematical model was developed to interpret the obtained respirometric curves. Closed respirometer experiments showed that phenol inhibited the respiration rate of unacclimated sludges. On the contrary, oxygen uptake rate (OUR) of phenol acclimated sludges exhibiting the typical Haldane's substrate inhibition curve. The Monod equation adequately represented the relation between OUR of acclimated biomass and DO concentration. Within the tested pH range (4-12) the oxygen saturation coefficient was independent of pH. On the contrary, the maximum OUR was strongly affected by the pH, being its maximum between 9.5 and 10.5. Open respirometer experiments shows that as pH decreased from 10.2 to 5.8, the maximum OUR also decreased, in accordance with the trend observed in the closed respirometer experiments. Although the respiration rate of phenol degrading bacteria was strongly affected by pH, a constant phenol oxidation coefficient was observed within the studied pH interval. A mathematical model was proposed to interpret the open respirometry curves. The coefficients of the model were estimated using both pseudo steady state and dynamic conditions for different biomass concentrations. The model adequately predicted the whole OUR and DO profiles as a function of time during the biodegradation of phenol under different DO conditions. The mathematical model proposed in the present work is useful for predicting transient responses such as substrate concentration and DO concentrations as a function of time in bioreactors treating phenolic wastewaters under an overload of phenolic compounds.
Assuntos
Fenol/metabolismo , Esgotos , Biodegradação Ambiental , Biomassa , Concentração de Íons de Hidrogênio , Oxigênio/metabolismoRESUMO
Los objetivos del trabajo fueron analizar la degradación biológica del fenol, utilizando barros activados aclimatados y no aclimatados a ducho sustrato y determinar los parámetros cinéticos y estequiométricos correspondientes, utilizando medidas respirométricas. Por otra parte se realizaron ensayos utilizando un respirometro abierto para obtener el coeficiente de oxidación del fenol
Assuntos
Fenóis , Lodos Ativados , Purificação da Água , ArgentinaRESUMO
Los objetivos del trabajo fueron analizar la degradación biológica del fenol, utilizando barros activados aclimatados y no aclimatados a ducho sustrato y determinar los parámetros cinéticos y estequiométricos correspondientes, utilizando medidas respirométricas. Por otra parte se realizaron ensayos utilizando un respirometro abierto para obtener el coeficiente de oxidación del fenol
Assuntos
Purificação da Água , Fenóis , Lodos Ativados , ArgentinaRESUMO
Las industrias metalúrgicas, curtiembre y químicas, descargan aguas residuales con gran contenido de cromo y deben ser tratados para evitar problemas ambientales. El uso de cultivos mixtos como por ej. barros activados, para la remoción de cromo hexavalente, parece ser una tecnología económicamente viable y prometedora. El artículo analiza el efecto de diferentes sustratos dadores de electrones, sobre la remoción de cromo hevalente en barros activados e investigar el efectos de la concentración de biomasa sobre la remoción de Cr(VI)
Assuntos
Cromo , Lodos Ativados , Remoção de Contaminantes , Tratamento de Efluentes IndustriaisRESUMO
Las industrias metalúrgicas, curtiembre y químicas, descargan aguas residuales con gran contenido de cromo y deben ser tratados para evitar problemas ambientales. El uso de cultivos mixtos como por ej. barros activados, para la remoción de cromo hexavalente, parece ser una tecnología económicamente viable y prometedora. El artículo analiza el efecto de diferentes sustratos dadores de electrones, sobre la remoción de cromo hevalente en barros activados e investigar el efectos de la concentración de biomasa sobre la remoción de Cr(VI)
Assuntos
Tratamento de Efluentes Industriais , Cromo , Lodos Ativados , Remoção de ContaminantesRESUMO
El objetivo de este trabajo es determinar la velocidad específica máxima de consumo sustentable, velocidad específica máxima de consumo de oxígeno, constante de saturación y el coeficiente de oxidación del sustrato correspondiente a bacterias heterótrofas y autótrofas utilizando un repirómetro abierto. Para los cultivos heterotróficos se determinaron parámetros cinéticos y estequiométricos que caracterizan la biodegradación de glucosa, lactosa y galactosa. En el caso de cultivos autótrofos se empleó sulfato de amonio como sustrato oxidable. A partir de los resultados obtenidos se puede concluir que la respirometría abierta permite la determinación de los parámetros cinéticos de biodegradación de diferentes compuestos en forma rápida y precisa
Assuntos
Respiração Endógena , NitratosRESUMO
El objetivo de este trabajo es determinar la velocidad específica máxima de consumo sustentable, velocidad específica máxima de consumo de oxígeno, constante de saturación y el coeficiente de oxidación del sustrato correspondiente a bacterias heterótrofas y autótrofas utilizando un repirómetro abierto. Para los cultivos heterotróficos se determinaron parámetros cinéticos y estequiométricos que caracterizan la biodegradación de glucosa, lactosa y galactosa. En el caso de cultivos autótrofos se empleó sulfato de amonio como sustrato oxidable. A partir de los resultados obtenidos se puede concluir que la respirometría abierta permite la determinación de los parámetros cinéticos de biodegradación de diferentes compuestos en forma rápida y precisa
RESUMO
El tratamiento de aguas residuales con alta concentración de materia orgánica soluble por barros activados suele presentar problemas en la sedimentación de los mismos, afectando la eficacia del tratamiento. Este trabajo tiene como objetivos determinar los requerimientos mínimos de nitrógeno o fósforo necesarios en un efluente de la industria láctea, estudiar el efecto que produce su deficiencia sobre la sedimentabilidad y la microflora de los barros obtenidos en esas condiciones, y analizar la influencia de modificaciones